CSP02 - Identifying the cause of a plunger pump shutdown data logging to the rescue

Abstract

When a plunger pump shuts down unexpectedly, there can be many potential causes. This case study demonstrates how a multi-channel data logging system was used to diagnose a mysterious shutdown of a plunger pump driven by a variable frequency drive motor through a gearbox. The pump operated normally for approximately seven days before mysterious shutdowns started to occur due to an over-voltage alarm on the motor VFD (variable frequency drive). Many steps were taken to diagnose the reason for the shutdown, however, there was no conclusive indicator of the cause. A complete overhaul of the pump was undertaken, but the same behavior occurred with the pump operating well for about seven days after which the shutdowns began at even more frequent intervals. A set of instrumentation was added to the pump, gearbox and motor with the intent to record all measurements after the latest shutdown and overhaul. Based on the collection and analysis of these measurements, we were able to capture detailed conditions at the next occurrence of a shutdown, which allowed us to determine the cause of the shutdown and recommend a successful solution.